Throughout history, efforts have been made to control fouling organisms that attach to ships. These efforts have met with varying degrees of success.
Prolonged and untreated fouling results in a degradation in the engineering properties of the ship's components and can lead to eventual destruction of the ship's structure. The plants and animals that constitute foulant material generally occur naturally in shallow waters along coastlines throughout the world. There are approximately 2,000 species of fouling organisms. The dominant type of fouling organism varies with location, air and water temperature, and time of year. Control of these organisms needs to occur before attachment to the surface of the ship, and an effective method of removal of any organisms that do attach is also critical.
Most of the efforts to control fouling in recent years have concentrated on the development of coatings for ships' hulls. Progress has been made in the development of these coatings. However, due to the sheer numbers, variety and complexity of marine organisms, finding one coating that can be effective under all conditions is extremely difficult.
Currently, the most common method of removing foulant once the organisms attach requires the boat to first be dry docked. Once in dry dock, a cavitating jet fouling removal device is used, which consists of high pressure water pumped through nozzles mounted on a carriage that moves along the side of the hull of the ship.
A search has revealed the following potentially relevant issued patents:
U.S. Pat. No. 3,505,758; U.S. Pat. No. 3,570,256; U.S. Pat. No. 3,581,505; U.S. Pat. No. 3,685,477; U.S. Pat. No. 4,026,233; U.S. Pat. No. 4,046,094; U.S. Pat. No. 4,058,075; U.S. Pat. No. 4,215,644; U.S. Pat. No. 4,244,749; U.S. Pat. No. 4,280,436; U.S. Pat. No. 4,280,437; U.S. Pat. No. 4,280,438; U.S. Pat. No. 4,280,439; U.S. Pat. No. 4,282,822; U.S. Pat. No. 4,289,423; U.S. Pat. No. 4,444,146; U.S. Pat. No. 4,693,200; U.S. Pat. No. 4,890,567; U.S. Pat. No. 4,943,954; U.S. Pat. No. 4,998,496; U.S. Pat. No. 5,138,963; U.S. Pat. No. 5,143,011; U.S. Pat. No. 5,152,242; U.S. Pat. No. 5,279,244; U.S. Pat. No. 5,465,676; U.S. Pat. No. 5,651,326; and U.S. Pat. No. 5,735,226.